Paper sized with an isocyanate-modified silicone



United States Patent 3,419,422 PAPER SIZED WITH AN ISOCYANATE- MODIFIED SILICONE Enrico J. Pepe, Kenmore, N.Y., assignor to Union Carbide Corporation, a corporation of New York No Drawing. Continuation-impart of application Ser. No. 307,003, Sept. 6, 1963. This application Jan. 27, 1966, Ser. No. 523,257

4 Claims. (Cl. 117-155) ABSTRACT OF THE DISCLOSURE Treated fibrous material having on at least the surface portion thereof of an isocyanate-modified silicone compound and being present on the paper in an amount at least sufficient to enhance the resistance of the paper to wetting by an aqueous medium, which isocyanatemodified silicone compound contains the isocyanate therein directly bonded to an organo group which in turn is bonded to silicon of the silicone by a carbon to silicon bond.

This application is a continuation-in-part of U.S. Ser. No. 307,003, filed Sept. 6, 1963, now abandoned.

The invention relates to paper making. In one aspect this invention is directed to a method for sizing paper or similar cellulosic fibers and the article of manufacture derived therefrom.

Cellulosic fibers constitute the bulk of finished paper. In addition thereto, however, a wide variety of internally contained or surface carried ingredients are employed to impart particular desired properties to the paper. These ingredients include fillers such as clay, chalk, and other oxides or salts of metals, dyes and colorant materials, mordants, retention aids, wet strength agents, sizing agents, and the like.

Paper is sized in order to increase its resistance to penetration by liquids, particularly water. The most common sizing system is rosi soap (sodium rosinate) and papermakers alum (aluminum sulfate). In addition to these, hydrocarbon and natural waxes, starch, sodium silicate, glues, casein, synthetic resins, latices, etc., have been employed as sizing agents.

As with almost all papermaking operations, sizing still retains 'much of the empiricism and art of earlier times. The techniques of sizing are many and varied, and they depend ;upon such variables as pH, temperature, other chemicals present, fiber type and condition. The exact mechanism of sizing also varies with the particular sizing agent employed, and in most instances is still the subject of controversy. For example, when rosin and papermakers alum are used, it is still a generally accepted but unproven theory that sizing is achieved by virtue of a colloidal system in which the negatively charged fibers hold a layer of positively charged aluminum hydroxide particles which, in turn, hold the negatively charged rosin. Such a theory is not necessarily valid with respect to other sizing agents such as glue or a natural wax.

In addition to the variety of mechanisms apparently involved with different sizing agents, it is not possible to predict as a rule the sizing effect any particular agent will have on one material from knowledge of the same sizing agent on a diiferent material or substrate.

Silicones containing relatively large amounts of methylhydrogen siloxane heretofore have been reported as sizing agents for paper. Such materials suffer from three major shortcomings, however: (a) considerable time is required to develop lasting water resistance under conventional paper treating conditions, (b) the useful lift of the silicone is shortened to impractical time periods when the silicone is used in conjunction with catalysts 3,419,422 Patented Dec. 31, 1968 which shorten the necessary cure time, and (c) the presence of even small amounts of alum in the paper further retards the development of water resistance. The sizing agents contemplated by the present invention contain no silanic hydrogen.

It is the principal object of this invention to obviate the aforesaid difiiculties while at the same time providing excellent, stable, silicon-containing sizing agents for cellulosic fibers which can be effectively used at relatively low loading concentrations.

It is another object to provide high quality sized cellulosic materials such as high quality sized paper.

It is a still another object to provide a method for sizing cellulosic fibers.

A further object of this invention is to provide a method for rending cellulosic materials adhesive.

These and other objects will become readily apparent to the skilled artisan upon reference to the ensuing specification and claims. t

The objects of this invention are achieved by sized cellulosic fibers, such as paper, characterized by the presence on at least the surface portion thereof of an isocyanate-rnodified silicone compound. The isocyanatemodified silicone compound is present on the cellulosic substrate in an amount at least suflicient to enhance the resistance of the cellulosic substrate to wetting by an aqueous medium.

The amount of the isocyanate-modified silicone present in or on the final product depends on the intended end use of the product. As soon as some increase in resistance to wetting is discernible, as compared to the untreated state, the treated cellulosic fiber can be deemed sized. In the case of cellulosic materials such as paper the degree of sizing can be carried on until a substantially continuous layer of the sizing agent, i. e., the isocyanatemodified silicone, is deposited on the surface. In the latter case the porosity of the sized material is considerably reduced. Also, when the material is sized to such a degree, i.e., hard sized, the material will exhibit release or abhesive, properties. However, even in the case of hard size the thickness of the addition product layer on the surface of the sized cellulosic material usually does not exceed about one-half mil. Thicker layers can be produced of course; however, no additional commensurate benefits can be gained thereby.

For sizing cellulosic fibers such as cotton cloth the isocyanate-modified silicone compound loading typically can be in the range from about 0.2 to about 3 weight percent, based on the weight of the dry fibers.

The method of this invention can be practiced either before, during, or after the paper forming operation. The isocyanate-modified silicone can be contacted with or applied to the paper fibers by itself, as a solution in a compatible solvent, or as an emulsion.

If this sizing agent is applied as a solution, typical compatible solvents are the aliphatic or aromatic solvents such as hexane, mineral spirits, kerosene, toluene, xylene, and the like. Also compatible are the halogenated solvents such as perchloroethylene and the like.

If the sizing agent is contacted with the cellulosic fibers as an emulsion, which in many cases, particularly in the treating of cotton cloth, may be very desirable, any of the conventional anionic, cationic, non-ionic emulsifiers, or compatible mixtures thereof, may be utilized. The amount and the exact type of emulsifier is generally determined by practical considerations with respect to the applyication procedure followed, emulsion stability, and minimum interference to the hydrophobing properties of the addition product. For emulsification the nonionic emulsifiers such as polyvinyl alcohol, trimethylnonylpolyethyleen glycol/nonyl phenyl polyoxyethylene glycol ether blends, polyoxyethylene sorbitan monooleate,

and the like, are preferred. Excellent emulsions exhibiting very good sizing properties have been obtained by premixing the non-ionic emulsifier, water, and the isocyanate-modified silicon compound in a suitable container and then passing the resulting admixture through a homogenizer at a relatively high (about 4500 p.s.i.) pressure.

The adition of the sizing agent to the paper fibers prior to the time when they are interfelted into a relatively low water content, self-supporting sheet is conventionally referred to as Wet end sizing. Similarly, when the sizing agent is applied to the already formed paper, the process is conventionally termed dry end sizing.

When, according to this invention, the sizing agent is applied to the Wet end of the papermaking process it can be applied in a water dispersible form such as ian aqueous emulsion, for example. As such it can be added to the water dispersed pulp at any time up until the fibers are picked up on the wire or cylinder of the paper machine. Preferably the addition is carried out after the beating operation which produces fibers from the starting material.

The optimum procedure for applying the sizing agent according to this invention at the dry end of the papermaking process depends on such factors as the type of papermaking equipment available, weight and speed of the paper, the desired degree of sizing, etc. Any conventional technique of application, such as a water box on a calender, tub sizing, size press, transfer roll, spraying, and the like, can be employed.

For sizing cotton cloth the conventional method comprises dipping the cloth in a treating bath which contains the sizing agent.

The sizing agents for the present invention are those isocyanate-modified silicone compounds which are (A) represented by the general formula Qu ]a SiX4(e+b) wherein Y can be a divalent or trivalent aliphatic or aromatic radical which is a member of the group consisting of a hydrocarbon, a hydrocarbon ester, and a hydrocarbon ether, the hydrocarbon portion of the foregoing being saturated or unsaturated;

Q can be an oxy (O-), thio (S), azo (N:N-),

carbamate substituted carbamate ureylene r t r (NC-N) or a tertiary amino nitrogen linkage;

R can be a monovalent aliphatic hydrocarbon, a monovalent cycloaliphatic hydrocarbon, a monovalent aliphatic halohydrocarbon, or a monovalent cycloaliphatic halohydrocarbon radical;

R can be a divalent aliphatic or aromatic hydrocarbon radical which is a member of the group consisting of a hydrocarbon, a hydrocarbon ether, a hydrocarbon ester, and a hydrocarbon tertiary amine, the foregoing being with or without substituents containing no active hydrogen such as halo groups, nitro groups, oggo groups,

4 nitrilegroups, hydrocarbonoxy groups (OR), and the like;

X can be a member of the group consisting of hydrogen, fluorine, chlorine, and hydrocarbonoxy (OR') groups; and a a has a value from 1 to 3 inclusive, b, has a value from 0 to 2 inclusive, with the proviso that the value of (a-f-b) is from 1 to 3 inclusive, d has a value from 1 to 2 inclusive, and e has a value from ()to 1 inclusive; (B) organosiloxane homopolyrners represented by the formula (II) R'b wherein Y, Q, R, R, a, b, d, and e represent the same groups and have the same numerical values specified in Formula I above; and (C) siloxane copolymers composed essentially of from about 0.1 to about 99.9 mole percent of units represented by Formula II and complementarily from about 99.9 to about 0.1 mole percent of units represented by the general formula wherein R" can be hydrogen or the same groups as represented by R in Formula 1 above, and ;f can have a value from 0 to 3 inclusive.

Illustrative of the radicals represented by R are the straight or branched chain alkyl groups such as methyl, ethyl, n-propyl, isopropyl, nbutyl, isoamyl, hexyl, decyl, octadecyl and the like; the cyclic alkyl groups such as cyclopentyl, cyclohexyl, bicycloheptyl, and the like; the aryl groups such as phenyl, naphthyl, p-phenylphenyl, and the like; the alkaryl groups such as neophyl, tolyl, xylenyl, and the like; the aralkyl groups such as benzyl, phenylethyl, and the like, the haloalkyl groups such as chloromethyl, chloroethyl, bromoethyl, chlorohexyl, and the like; the haloaryl groups such as chlorophenyl, chloronaphthyl, fluorophenyl, and the like. Preferably R is an alkyl group conatining from 1 to about 22 carbon atoms or a phenyl group. More preferably R is a methyl group.

Illustrative of the radicals represented by R are the alkylene groups such as methylene, propylene, ethylethylene, octylene, and the like; the cycloaliphatic radicals such as and the like; the hydrocarbon ether groups such as CH CH OCH CH 'CH CH CH OCH CH(CH and the like; the hydrocarbyl ester groups such as -CH2CH(CH3) C"O"CH2GH2 OH2CH2CHn?| OCHrCH2 and the like; the arylene groups such as phenylene, and the like; the aforementioned radicals with sustituents containing no active hydrogen such as chloro-methylene, bromopropylene, chlorophenylene, nitrophenylene CH2CH2CHCzCH2-, -CH2CH2CHCH2 GEN OCHzCHa and the like. Preferably R is an alkylene group containing from 1 to about 22 carbon atoms or a phenylene up- Illustrative of the radicals represented by Y are the alkylene groups such as ethylene, propylene, butylene, octylene, octadecylene, dodecylene, and the like; the alkylidene groups such as l-propanyl-B-ylidene, l-butanyl- 4-ylidene, and the like; the arylene groups such as phenylene, naphthenylene, and the like; the alkenylene groups such as vinylene, propenylene, and the like; the hydrocarbon ether groups such as CH CH OCH CH CH CH CH OCH CH(CH and the like; the hydrocarbon ester groups such as lLtOll NCO 2 (CHM NCO

Of course, the copolymers and homopolymers can be in the form of cyclics, linear fluids, branched fluids, gums, etc., depending upon the functionality of the component units.

Particularly preferred as sizing agents for paper are 6 the isocyanate-modified silicone systems of the general type wherein R is an alkylene group; R is an alkyl group or an aryl group; Z is an alkoxy group, an aroxy group, or a siloxane group having the formula R SiO b can have a value from 0 to 2, inclusive; x can have a value from 1 to 10 and preferably from 1 to y can have a value from 1 to 10 and c has a value of with the further proviso that the ratio of y-t-c to x is not greater than 10 and preferably is in the range from about 5 to about 500.

It has been found that these sizing agents can be prepared readily by contacting an aminohydrocarbylsilane or aminohydrocarbylsiloxane with phosgene, optionally in the presence of an inert organic solvent, at reaction temperatures to form the desired silicone isocyanate.

As starting materials for the preparation of the compounds of Formula I above, aminohydrocarbylsilanes are employed having the general formula wherein Y, Q, R, R", a, b, a, and e represent the same groups and values as in Formula I, and Z represents hydrogen or OR' groups. Similarly, the homopolymers and copolymers of Formulae II and III are prepared from the starting materials represented by the general formula KHZNMYQQR P w and aminohydrocarbylsiloxane copolymers represented by the general formula respectively, wherein Y, Q, R, R, a, b, d, e, and f represent the same groups and values as in Formulae II and III, and g and h are integers such that the units of the formula RSiO represent from 0.1 to 99.9 mole percent of the copolymer.

The relative proportions of phosgene to the aminohydrocar-byl silicone is not a narrowly critical factor, but for efficient and complete reaction it is preferred to employ approximately 3 to 5 times the stoichiometric requirement of phosgene. Stoichiometrically one molecule of phosgene is necessary to convert one NH group to an N=C:O group. Thus for each mole of aminohydrocarbyl silicone the theoretically required molar amount of phosgene is equal numerically to the average number of NH group per aminoalkyl or aminoaryl silicone molecule.

It is believed that the reaction of the aminoalkyl or aminoaryl silicone with phosgene proceeds by a two-step reaction in which the products of the first reaction are a canbamic acid chloride and an amine hydrochloride, which intermediates are each converted to the desired isocyanate by additional phosgene. In equation form these reactions can be illustrated by the following (J representing the grouping YQ R supra): I? HzN-J-SiE 00012 HCLNHrJSiE ClC-NHJSi HCl'NIiZJSlE The first reaction (1) is favored by relatively low temperatures, generally of the order of about C. to about C., Whereas the seuond reaction (2) is generally favored by elevated temperatures. In general optimum results are obtained from the second rection step in the case of aminoalkyl silicones by employing temperatures within the range from about 100 C. to 200 C., preferably about 175 C. In the case of aminoaryl siloxanes temperatures of from about 50 C. to about 100 C. are preferred in order to avoid splitting of siloxane bonds with a consequent lessening of yield. It is, therefore, advantageous to initially contact the aminosiloxane with phosgene at low temperatures and slowly raise the reaction temperature as the reaction progresses until reaction is substantially complete.

The reaction of phosgene with the amino group of the starting silicon compounds is favored, particularly at lower temperatures over the competing reaction of phosgene with any hydrocarbonoxy groups bonded to silicon which happen to also be present in the same starting compounds. In general, however at temperatures which permit optimum reaction rates, some hydrocarbonoxy substituents are converted to chlorine su'bstituents, thereby giving rise to a mixed reaction product which is readily separated by conventional procedures such as distillation. Chlorine attached to silicon is readily replaced by fluorine by contacting the chlorine-containing product with sodium fiuorosilicate at moderately elevated temperatures.

A preferred means of obtaining intimate contact between the reactant materials is the utilization of an inert organic solvent medium in which at least the phosgene is soluble and preferably the aminohydrocarbyl silicone also. Illustrative of those conventional solvents are toluene, benzene, chlorobenzene, 4-chloro-ethylbenzene, xylene, and carbon tetrachloride. Preferably the solvent is a high boiling halogenated hydrocarbon. When necessary to raise the boiling temperature of a desired solvent to attain optimum reaction temperatures, superatrnospheric pressures can be employed, with provision being made for the removal of HCl from the reaction system. Reactions are generally carried out under normal atmospheric or slightly reduced pressures using an inert gas purge such as nitrogen or helium.

- Any kind of fibrous cellulosic material such as wood or cotton can be subject to the present sizing treatment. Paper to be sized can be made using any type of wood, pulping procedure, bleaching procedure, etc. The paper can also contain fillers such as clay, titanium dioxide, calcium carbonate, and the like, and can also contain the conventional papermakers additives such as starch, rosin, and wet strength resins. Typical types of paper that can be sized in accordance with the present invention are made from (1) reclaimed ground wood, (2) unbleached soft wood-kraft, (3) bleached soft wood and mixed hardwood; the soft woods having been prepared by the sulfate, sulfite, or soda process, (4) highly hydrated pulps supercalendered to a smooth, dense paper, and the like.

Sizing is complete as soon as the paper treated with the sizing agent in accordance with this inveniton has dried. It is usually not necessary to subject the treated paper to elevated temperatures to effect a cure. Of course, elevated temperatures can be employed during drying without any adverse effect provided the degradation temperatures of the fiber, paper or the sizing agent are not exceeded.

As pointed out before, sizing is effective as soon as a sufficient amount of the sizing agent is deposited on the cellulosic fibers to enhance the wetting resistance of the paper as compared to that of an untreated sample of the same fibers. Generally, relatively small amounts of the sizing agent are necessary to attain this end. For example, a satisfactory size of paper used for the manufacture of gypsum board was obtained with about 0.2 lb. of the instant sizing agent per one ton of lb./ 1000 sq. ft. paper.

The amount of the sizing agent necessary to impart abhesive properties to paper is dependent upon the porosity of the paper. Usually the loadings are in the range from about 0.01 to about 4 pounds of the sizing agent per 3000 square feet of paper. Loadings in the range from about 0.1 to about 2 pounds per 3000 square feet of paper are preferred.

Usually no catalyst is necessary when the isocyanatemodified silicones are employed as sizing agents. However a catalyst such as dibutyltin dilaurate can be utilized to enhance a cure if desired. Other suitable catalysts are strong bases, nitrogen compounds such as triethylene diamine, tetramethyl guanidine, the N-alkylethyleneimines, etc., organotitanium compounds, organotin compounds, metals such as lead, iron, tin, and the like.

Also, the use of the isocyanate-modified silicones as sizing agents for paper does not preclude the use of resins and/or other organic additives such as the retention aids commonly employed in the papermaking art. T ypica-l of such materials are starch, polyvinyl alcohol, carboxymethyl cellulose, gum, urea formaldehyde resins, melamine-formaldehyde resins, rosin, the sulfonium methyl sulfate salt of acrylic acid-acrylamide copolymers, amineepichlorohydrin derivatives, and the like. Similarly, the presence of the commonly employed wash-and-wear resins used in conjunction with cotton fabrics is not precluded.

This invention is further illustrated by the following examples.

EXAMPLE I (CHiOaNCO S|i(OC:H O

K ahS Ohso using a hand homogenizer. The resulting emulsion was then diluted with additional water to a silicone concentration of about 0.45 wt. percent.

Paper handsheets were made in a Noble and Wood sheetmold using a mixture of 50 wt. percent bleached kraft softwood and 50 wt. percent bleached sulfite softwood. About 25 wt. percent clay was also added to the foregoing mixture. The resulting paper sheets were then dried for about 3 minutes at about 88 C. F.) in a Noble and Wood drum drier. The paper weighed about 2.5 grams per handsheet or about 46 pounds per 3000 ft.

The diluted emulsion containing the isocyanate-modified silicone was then applied on the handsheets using a laboratory calender operating at about 400 ft./ min. and equipped with a water box on the lower roll so as to give a silicone loading on the handsheet of about 0.1 weight percent, based on the dry weight of the paper.

After the silicone application the paper was dried for about 3 minutes at about 88 C. (190 F.) and conditioned overnight at about 24 C. (75 R).

Water resistance was measured using a tester which indicates the time for water to penetrate the paper. For the silicone treated paper the time for water penetration was about 52 seconds whereas water penetrated an untreated sample of the same paper in less than one second.

The dilute silicone emulsion was then aged for about 7 hours at room temperature and then applied on paper in the aforedescribed manner. The treated paper had a water penetration time of about 47 seconds which is within the experimental limits, i.e., the performance of the aged emulsion was about the same as that of the fresh emulsion. This demonstrates the stability of the paper sizing emulsion of this invention.

EXAMPLE II An aliquot of the emulsion prepared in Example I was admixed with cooked corn starch so as to obtain a starch to silicone ratio of about 13:1. The resulting blend was then diluted with water and applied to handsheets of 46 lb./ 3000 ft. paper. The paper was made from a pulp blend of 50 wt. percent sulfate softwood, 25 wt. percent sulfite softwood, and 25 wt. percent sulfite hardwood.

The starch/silicone blend was applied to the paper using a laboratory calender operating at about 200 ft./ min. and equipped with a water box so as to give a silicone loading on the paper of about 0.1 weight percent, based on the dry weight of the paper.

After the silicone application the paper was dried for about 3 minutes at about 88 C. (190 F.) using a drum drier. The treated paper was tested for water repellency as. soon as it was removed from the drier by placing thereon drops of water. The treated paper did not wet in 2 to 3 minutes which indicates good size. Without the treatment with the isocyanate-modified silicone the water drops wet the paper within several seconds.

EXAMPLE IH An aliquot of the emulsion prepared in Example I was applied to several types of paper using a laboratory calender equipped with a water box on the lower roll. In all cases the silicone loading on the treated paper was about 0.1 weight percent, based on the dry paper. After treating the paper was dried for about 3 minutes at about 88 C. (190 F.) and then conditioned for one dayat about 24 C. (75 F.) and 50% relative humidity. All of the treated paper was found to be water resistant, i.e., sized. The table below summarizes the types of paper treated.

based on the pulp, and sufficient sulfuric acid to give a pH of about 4.5 for thepulp suspension.

All of the foregoing ingredients were then stirred together for about 19 minutes. The resulting suspension was then diluted 1:5 with tap water and made into paper handsheets weighing about 46 lbs/3000 fL A Noble and Wood sheet mold was used.

The resulting paper was then dried for about 3 minutes at about 88 C. (190 F.). The paper was water resistant as soon as it was dried.

Some of the paper manufactured in above manner was conditioned for about one day at about 24 C. (75 F.) and relative humidity and then tested for water resistance. The time needed. for Water to penetrate the treated paper was in the range from about 35 to about 80 seconds. The time needed for water to penetrate an untreated sample of similar paper was less than one second.

EXAMPLE V The isocyanate-modified silicone having the general formula (CHMNCO 2 was emulsified in water withabout 3 weight percent of trimethylnonylpolyethylene glycol ether and about 2 weight percent of nonylphenylpolyethylene glycol ether, based on the weight of the silicone present. To the resulting emulsion then was added the sulfonium methyl sulfate salt of an acrylic acid-'acrylamide copolymer as a retention aid (about 20 weight percent, based on the weight of silicone).

The thus prepared emulsion was then admixed with a pulp suspension (50 wt.-percent bleached kraft, 25 Wt. percent bleached, sulfite, and 25 wt.-percent bleached soda hardwood) also containing about 20 wt.-percent clay and about 5 wt.-percent corn starch, based on the dry weight of pulp. The pulp was at a consistency of about 23.7 grams per 18 liters of the suspension and the silicone concentration in the pulp suspension was about 0.5 weight percent, based on the dry weight of the pulp.

TABLE I Percent Pulp Composition, weight percent Weight] Clay Type Paper 3,000 it. Added Sulfate Sulfite Semi- Sulphate Sulphite Semito softwood softwood chemical hardwood hardwood chemical Beater softwood hardwood Handsheets 46 25 Unsized commercial 18 0 20 Handsheets 46 0 Handsheets 46 20 EXAMPLE IV An aqueous emulsion was prepared from water (about 139 grams), a 10 wt.-percent aqueous solution of polyvinylalcohol (about 20 grams), a sulfonated aliphatic polyester (about 1.2 grams), and an isocyanate-modified silicone (about 40 grams) having the general formula (CHzhNOO S|i(OC2H5)Z 0 2 using a hand homogenizer.

Unbleached graft pulp was beaten to a Canadian Freeness of about 505 ml. and diluted to about 23.7 grams of pulp per 18 liters of tap water. To the diluted pulp suspension then was added the above silicone emulsion in an amount to give a silicone concentration of about 0.5 weight percent, based on the pulp.

Thereafter sufl'icient aluminum sulfate was added to the pulp to give a concentration of about 0.1 Weight percent,

After the silicone-containing pulp suspension was mixed for about 10 minutes, the suspension was diluted 1:5 with tap water, made into handsheets in the manner set forth in Example IV. H

The thus produced paper was then conditioned for about one day at about 24 C. F.) and 50% relative humidity and then its water resistance was evaluated. The time needed for water to penetrate the treated paper was in the range from about 41 to about 52 seconds. The time needed for water to penetrate an untreated sample of similar paper was found to be less than one seconds.

EXAMPLE VI An isocyanate-modified silicone having the general formula K ahsiOhao 1 l 12 was emulsified in water with about weight percent of N- pellency using the AATCC Spray Test (Method 22-1952) cetylethylmorpholinium ethosulfate, based on the weight whereby 250 ml. of water is sprayed on the cloth and the of the solicone present. cloth evaluated for water repellency. A zero rating means The prepared emulsion was then admixed with a pulp the cloth was comPletely waited, a rating of 100 suspension (50 wt.-percent bleached softwood kraft, 5 means that Water dld not Wet or Stlck To the 610thwt.-percent bleached sulfate softwood, and 25 wt.-percent Thereafter the treated cloths were washed repeatedly hardwood kraft) also containing about 20 wt.-percent in a Kenmore automatic washing machine using about 80 clay and about 0.5 wt.-pcrcent cationic starch, based on grams of a household detergent, a low water level, a

the dry weight of the pulp. The pulp was at a consistency water temperature of about 71 C. (160 F.), and washof about 23.7 grams per 18 liters of the suspension, and 10 ing cycle A. After each wash cycle the cloth was air dried.

the silicone concentration in the pulp suspension was Because of the relatvely high water temperature employed about 0.5 weight percent, based on the dry weight of the this is considered to be a severe wash test. The experipulp. mental results are compiled in Table II below.

TABLE II Spray Rating (AATCC 22-1952) Silicone Catalyst Based on Silicone Drying cond. Initial 3 5 Washes Washes (oHmsiol(oHn siolmomsiorH NoonnsttOm); 10 ay t. per cent dibutyl tin Brain. at 100 0 100 so so 1 aura 0- None 5mtirfigt00 O.+3 min. 100 80 80 a Control, (CH )zSiO[(CH3)HSiO]:0-40Si(OHa)3 11 wt. percent zinc octoate do 100 50 0 Untreated cotton cloth 0 After the silicone-containing pulp suspension was mixed The data indicate that a treatment with the isocyanatefor about 5 minutes, the suspension Was diluted 1:5 with modified silicone compounds provides substantially imtap water and made into handsheets in the manner set proved water repellency properties to cellulosic fibers, forth in Example 1V except that the effiuent from the i.e., cotton cloth. deckle box, i.e., the White water, was recirculated to EXAMPLE VIII the pulp suspension.

Paper produced using the recycled White water" was conditioned for about one day at about 24 C. (75 F.)

An isocyanate-modified silicone compound having the structural formula and 50% relative humidity, and then its water resistance was evaluated. The time needed for water penetration of 0 CH3 I the treated paper was observed to be about 43 seconds, g g whereas, similar untreated paper was penetrated by the 1 L1 1 water in about one second. (CHm 200 NCO 4 EXAMPLE v11 was dissolved in hexane so as to produce a solution containing about 4 weight percent silicone. In addition dibutyltin dilaurate was introduced into the solution as a catalyst in an amount of about 1 weight percent, based 45 on the amount of the silicone present.

The resulting solution was then applied on 40 pounds/ Emulsions were prepared from an isocyanate-modified silicone compound (about 20 parts by weight), polyoxyethylene esters of mixed fatty acids and resin acids (about 1 part by weight), N-cetylethyl morpholinium ethosulfate (about 1.1 parts by weight), and water (about 78 parts by weight). In addition, a control emulsion was prepared ream glassine Paper using an applicator bat made by 3 slhcone on having the general formula wrapping a steel rod (No. 8 RDS rod) with a wire so as (C1{ 5i()[(CH )1-ISiO] Si(CI-I to produce silicone loadings of about 0.2 and 0.4 pound per 3000 square feet of paper, i.e., 0.2 and 0.4 p.p.r. (about 40 parts by weight), polyoxyethylene esters of Thereafter the resulting treated paper was heated for mixed fatty acids and resin acids (about 4 parts by about 40 seconds at a temperature of about 163 C. weight), water (about 56 parts by weight), and sufficient (325 F.) to remove the solvent and to cure the silicone. acetic acid to give a pH of about 4.5. The glassine paper treated in the aforedescribed man- A first catalyst emulsion was prepared by admixing dinor was then tested for water repellency and for abhesive butyltin dilaurate (about 37.5 parts by weight), polyoxyor release properties. When a drop of Water was placed ethylene sorbitan monooleate (about 2.96 parts by on the treated paper no wetting was observed, whereas weight), a mixture of monoand di-glycerides of fatuntreated paper was readily wetted by a water drop. When forming fatty acids (about 0.74 part by weight), and wapressure sensitive cellophane tape was applied to the surter (about 57.8 parts by weight). A second catalyst emul- 60 face of the treated paper, firmly pressed on by rubbing the sion was prepared by admixing zinc octoate (about 39 applied tape with a finger, and subsequentlyremoved, the parts by weight), polyoxyethylene sorbitan monooleate removal was very easy, and no paper fibers were stuck (about 3.12 parts by weight), a mixture of monoand dito the removed tape. When the same procedure was carglycerides of fat-forming fatty acids (about 0.78 part by ried out with untreated glassine paper the removal of weight), and water (about 57.1 parts by weight). the tape from the paper was difficult and paper fibers Treating baths were then prepared by diluting the siliwere stuck to the tape after its removal from the paper. cone-containing emulsions with water to a silicone content After removal of the pressure sensitive cellophane tape of about 2 weight percent and by adding a catalyst emulfrom the paper treated with the isocyanate-modified silision in an amount sufiicient to provide the catalyst concone compound the tape was applied to untreated paper centration indicated in Table II below and white cotton and was observed to stick. This indicates that the sizing cloth (80 x 80 threads per inch) was passed therethrough. ag nt had not migrated from the treated paper to the Excess liquid was squeezed out of the cloth as the cloth tape. left the treating bath by means of padder rolls, and the Th6 treated P p was further tested i g T PI C- cloth dried, 283 Release and Subsequent Adhesion Test (migration).

The dried, treated cloth was then tested for water re- This test measures the force required to strip surgical ad- 13 14 hesive tape from a treated surface after tape-to-surface 2. Paper sized in accordance with claim 1 wherein the contact of 20 hours at about 70 C. (to accelerate the isocyanate-modified silicone compound is represented by test) and 0.25 p.s.i. contact pressure. As indicated in the formula Table III below, the paper treated with an isocyanate- OONRSiO modified silicone compound exhibited good release or I it?) b abhesive properties with no indication of migration of the R b 2 silicone compound. where R is an alkylene group; R is an alkyl group or an TABLE III Release of Surgical Catalyst Water Tape hours/ Age of Loading Repellency Release of 70 C./0.25 p.s.i.)

Solution (p.p.r.) (Water Cellophane Remarks Wt. Percent, Drop .Tape Release Subs. Type Based on Test (gJinch) Adhesion Silicone (g./inch) Dilbutyltin dilaurate 1 0 hour 0. 4 240 450 Do 1 0 hour 0.2 310 430 Do 1 24 hours 0.2 .1 230 410 Do 1 24 hours 0. 4 .do (10.. 280 450 Untreated Control Poor Poor 650 240 l Fibers were picked from the paper.

EXAMPLE IX aryl group; Z is an alkoxy group, an aroxy group, or a The isocyanate-modified silicone compound set forth slloxane group haying t formula Rarslol/z; b in Example VIII was emulsified in water using about 10 Value from 0 to mcluslve; i has value from 1 to 10 weight percent, based on the Weight of the silicone, of 25 yfhas a from 1 to Inclusive; a c has a value an equal weight blend of polyoxyethylene esters of mixed 0 I l 3 b fatty and resin acids and of N-cetyl-ethyl morpholinium ethosulfate. The silicone concentration in the resulting 2 aqueous emulsion was about 1 weight percent. No catalyst with the further proviso that the ratio of y+c to x is was employed.

u not greater than 1000.

Th6 aqueous emulsion was then PP t0 commel'clal 3. Paper sized in accordance with claim 1 wherein the n l d K t P p using a Wife Wound pP isocyanate-mod ified silicone compound is represented by bar (No. 18 RDS rod), and the treated paper was then the f l heated for two minutes at about 113 C. (235 F.).

The treated paper was observed to be water repellent. (CHmNCO Pressure sensitive cellophane tape, when applied to the li(OC2H5)2 [wfimsiolm treated paper, released easily without any pickup of paper o fibers, and subsequently did adhere to untreated paper L l 2 when applied thereto. In addition, the more severe Release 4, Cellulosic fiber sized with an isocyanate-modifie'd and Subsequent Adhesion Test (TAPPI RC-283) de- 40 silicone compound which is provided on the fiber in an ribed in Example VIII was also employed, and good amount at least sufficient to effect enhancement of the release was Obtained with the treated paper (about 635 resistance of the fiber to wetting by an aqueous medium, g./inch, as compared to about 900 g./inch for the unwhich isocyanate-modified silicone compound contains the treated paper). The surgical adhesion tape did nOt pick isocyanate thef ein directly bonded to organo group up any fibers upon removal from the treated paper and which in turn jis bonded to silicon of the silicone by a did adhere to untreated paper when applied thereto subcarbon t ili b sequent to the removal of the surgical tape from the surface of the treated paper. Thus no migration of the iso- References Cited cyanate-modified silicone compound from the surface of UEITED STATES PATENTS the treated paper took place. p

The foregoing discussion and the examples are to be 3,170,891 21/1965 speler 260-37 taken as illustrative. Still other variations within the spirit 3,178,391 4/1965 Holtschmldt et 260-465 and scope of this invention will readily present themselves 3,179,622 4/1965 Haluska 26046-5 to one Skilled in the art 3,012,006 1211961 Holbrook et al 260-465 I claim; 3,179,713 4/1965 Brown 117-161 1. Paper sized with an isocyanate-modified silicone 2,893,898 7/1959 Evans et 117138-8 compound which is provided on the paper in an amount at least sufficient to effect enhancement of the resistance WILLIAM D MARTIN Exammer' of the paper to wetting by an aqueous medium, which T. G. DAVIS, Assistant Examiner. isocyanate-modified silicone compound contains the isocyanate therein directly bonded to an organo group which US. Cl. X.R.

in turn is bonded to silicon of the silicone by a carbon 117 143, 161; 162 164 to silicon bond. 

